Periodontal tissue that supports teeth consists generally of the alveolar bone, the periodontal ligament tissue forming the periodontal membrane between the alveolar bone and the teeth, and the connective tissue. The loss of alveolar bone caused by the progression of periodontitis involves the loss of periodontal ligament tissue, and at sites with the loss of periodontal ligament tissue, the normal repair of alveolar bone and periodontal ligament tissue after the treatment of periodontitis becomes impossible due to excessive growth of connective tissue. Also, even when new bone is formed, the periodontal ligament tissue will not be normally differentiated so that the loss of tooth function can be caused.
To solve such problems, an attempt to induce the complete regeneration or new formation of tissue using an artificial barrier membrane together with autografting in guided periodontal regeneration is actively made. Also, for the regeneration of bone tissue, a tissue engineering scaffold is used as a bone graft material. Since cases showing the effective induction of periodontal tissue and bone tissue by the introduction of bone graft materials and scaffolds (Camelo, M. et. al, International J. Periodont. Restorative Dent. 21:109, 2001) were reported for recent ten years, various materials, including bone powder particles made of bovine bone, have been used as bone materials and tissue engineering scaffolds for tissue regeneration.
Meanwhile, in order to improve the efficiency of such bone graft materials and scaffolds for tissue regeneration, studies to attach materials capable of improving tissue regeneration to the bone graft materials and the scaffolds are now conducted. Among such materials, extracellular matrices or specific tissue growth factors are reported to be excellent in the ability of the repair and regeneration of damaged tissue, and their excellent ability to regenerate tissue was also shown in the results of actual clinical tests.
However, there have been drawbacks that most of the extracellular matrices and growth factors are relatively expensive and are unstable in high-molecular weight living bodies having a molecular weight of several tens kDa, leading to a reduction in the activity. Particularly, there have been problems that they disappear in a few minutes so that they should be administered at high dose to achieve the desired therapeutic effect and thus, cause side effects.
Recently, there have been attempts to reduce shortcomings with a simple application of these materials by adding the tissue growth factors to bone graft materials used in guided bone regeneration and polymer scaffolds used in tissue engineering so as to induce sustained release of the tissue growth factors. Also, some effects of such attempts were proved. However, there is a disadvantage in that, with these bone graft materials or scaffolds themselves, the tissue growth factors are physically mixed, so that, in initial application, the burst release of the growth factors occur, thus making it difficult to maintain the tissue growth factors at an effective concentration for a treatment period.